This invention relates to dilution control of internal combustion engines subject to driveability problems associated with surge.
Surge is an engine roughness which is detectable by the vehicle operator and passengers and is associated with periodic engine rotational speed variations in a frequency range of substantially 2-10 Hz. The phenomenon is well known and has been described in the prior art.
There is a great deal of prior art showing engine roughness detectors, some of which deals particularly with the detection of surge as defined above. However, most of the prior art in this area dates from the era before the common use of microcomputers in engine control; and the roughness detectors shown are hard wired electronic circuits. With the advent of microcomputer engine control, these circuits and the processes embodied therein are no longer optimal.